1. Field of the Invention
This invention generally relates to the field of rotary driven cylindrical cutter devices and scarifiers for use in roadway surface reclaiming, earthworking, mining, or other in situ disintegration of hard materials. More particularly, the present invention is directed to cutter bit inserts for such rotary driven cylindrical cutter devices and scarifiers and the removal of such cutter bit inserts.
2. Background of the Invention
In general, roadway surface milling, planing, or reclaiming equipment disclosed in the prior art includes a rotary driven cylindrical comminuting drum which acts to scarify and to mine the top portion of the asphaltic road surface in situ. Another application using a rotary driven cylindrical comminuting drum is coal mining. Coal mining machines with shearing drums are used rather widely in mining, particularly in underground mining of bituminous coal. Regardless of the application, the rotary driven drum may include flighting on the drum which acts to collect the mined or milled material or rubble toward the center of the drum where the material can be removed. In roadway surface milling, the rubble is then remixed with additional bituminous material and thereafter redeposited as a newly formed smooth asphaltic surface. In coal mining, the loosened coal rubble is collected onto a pan line, taking the coal to the conveyor belt for removal from the work area to the surface where the rubble is further processed.
In some prior art devices of this type, a plurality of cutter bit support members are connected to the curved surface of the drum or to the flighting by bolts or by weld. The plurality of the support members may be arranged end-to-end so as to form a substantially continuous helical pattern. The top surface of the helically arranged support members may be elevated above the curved surface of the drum. The top surfaces include angled openings into which conventional cutter bits are received. The cutter bits are generally a conical cutter with preferably a tungsten carbide tip or the like. Optionally, the support member may include an opening for receiving cutter bit insert that is removably mounted to the support member, for instance by threaded attachment. The insert has an opening for receiving the cutter bit and a gripping surface used for inserting and removing the cutter bit inserts with respect to the support members.
One example of a cutter bit insert is disclosed in U.S. Pat. No. 5,842,747 to Latham. Here, the insert includes a gripping surface, a conical shoulder, and a lower surface, defines an interior bore for receiving a cutter bit, and has external threads capable of threaded engagement with threads of a base portion. The gripping surface allows for easy access for removal of inserts. Threaded jamming fastener is also disposed in threaded engagement with threads of the base portion. The jamming fastener is initially positioned below the insert by use of an appropriate tool in the jamming fastener opening. After the insert is in place, the appropriate tool again is inserted in the jamming fastener opening and rotated to translate the jamming fastener toward the lower end of the insert until contact. Accordingly, the reverse is true when removing such insert from the base portion, especially when the insert is damaged. However, when the gripping surface of the insert is damaged, it becomes difficult to remove the insert for replacement.
Damage to the inserts can be common. During use, abrasive forces, which often include rather substantial extreme sudden shocks, are transmitted to the cutter bits. Oftentimes, the forces are unevenly distributed between the cutter bits and inserts, which causes the cutter bits to vibrate and otherwise move and rotate within the support member opening or within the insert. Particularly in the presence of abrasive dust from the roadway surface reclaiming operation and the mining operation, the vibration and movement of the cutter bits act to enlarge the openings to such an extent that the cutter bits can be thrown out of the inserts. Indeed, depending on the abrasiveness of the mining surface, cutter bits and inserts can become damaged after about 4 hours to about 1 week of operation. It is desirable for the less expensive cutter bit to become damaged before the more expensive insert and even the more expensive and difficult to replace support member, in order to extend the life of the insert and the support member.
Unfortunately, the short life of cutter bits and/or inserts causes the mining machine to be stopped frequently for considerable lengths of time for repairs. In particular, repair and replacement of the insert damaged in this manner typically necessitates the use of an easy-out or similar removing tool in the field to remove the insert. Typically as a last resort, it becomes necessary to remove the support member portions, usually with the aid of a cutting torch, and to weld new support member portions in place. This is a time-consuming repair job which results in considerable expense to a mining machine operation, and results in a decreased rate in mining.
Despite the availability of such devices, there exists a need in the art for an apparatus and system having an insert for a roadway surface reclaiming drum that is capable of removable attachment to a base portion, yet is resistant to loosening upon rotation of the drum. There is also a need for the optimal removal of an insert, and in particular, an insert with a damaged gripping surface, in order to decrease the time and costs of repair and replacement.